Original Fender Telecaster Bass Humbucker - Anyone know if these were date stamped ?

Last Fall I picked up a White (now practically yellow) 1973 Fender MusicMaster Bass at a little country auction. This is not something I would play very often and was mainly into it for collecting or flipping. What was interesting about this particular bass was the home modification the original owner had done. This was equipped with an original Telecaster Bass Humbucker. The type Seth Lover had designed after being lured over from Gibson in 1968. To my knowledge, MusicMasters were always fitted with a lone single coil pickup, and generally not ones capable of stellar performance. The large Humbucker first appeared in the Telecaster bass in 1971. The mod itself was not bad, but not nice enough for me to dream that it could have possibly been a factory custom order. The pickup is probably worth more than the bass, having seen one recently on Gbase for close to $500. I wouldn't pay that much if I needed one, I guess authenticity can carry steep prices.

Does anybody know how to date these pickups ? There is a 4 digit code on the back of the pickup's metal rear housing and it looks like a stamp done in black ink. The code is 3375 or 3875, the 75 makes perfectly good sense if that is a date code, but I just don't know if that is indeed a date stamp. While I am familiar with Fender neck stamps and the dating of pots, I don't have any experience with this pickup. It also has me wondering if this was ripped from a Telecaster Bass or purchased from Fender. Could you buy pickups and other electronic parts like this from Fender in the 70s? The scavenging from the Tele Bass makes less sense, considering that would have been a fairly new Bass at the time of the mod. Plus the Tele would have been a much more desirable instrument. I doubt there were many aftermarket options at the time to cleanly do a pickup swap into the Tele bass besides that very pickup. So in addition to the main question about dating, I am curious if Fender parts were readily available to the public at that time. That would help answer some other mysteries that I have come across in the past. Any and all comments welcome. Looks like a good question for the Tele Bass club. Note: I put this topic here in Basses because its really more about dates and the semi-interesting bass find rather than electronics. Thanks.